It is expected that 25-35% of children with repaired cleft palate will have VPD as evidenced by hypernasal speech. If a child has a primary repair of the levator veli palatini (levator) muscle (i.e., primary muscle for velar elevation during speech) that does not conform to that of normal anatomy, it is likely that the child will develop hypernasa speech and will require secondary palate surgery. The primary cause of VPD is due to what we term disadvantageous biomechanics. Specifically, the anatomy and mechanics of the velopharyngeal (VP) mechanism post-surgically are not adequate for proper VP function. Our research team has demonstrated that surgical planning in which pre-surgical muscle arrangement and function are used to determine post-surgical structure is critical to a successful speech outcome. The goal of this proposal will be to develop subject-specific models based on magnetic resonance imaging data to determine how and why certain children have VPD following surgery. Our vision is to ultimately improve outcomes of cleft palate repair by providing a framework in which pre-surgical muscle arrangement and function are used to inform surgical plans to optimize post-surgical structure. Our goals are in this project are to: (i) determine whic anatomical features lead to disadvantageous biomechanics in children who have VPD, and (ii) reveal the ways in which the anatomy could be changed to restore normal VP function. We intend to achieve these goals through the following specific aims: (Aim 1) Create computational models of children with and without VPD who have had cleft palate repair; and (Aim 2) Use the subject-specific models to determine the cause of VPD in each child. After successful completion of this R21 project, we will have demonstrated that the subject-specific models are predictive of function in children post-cleft palate repair. These results will empower us to move towards modeling patients pre-repair and determining if patient-specific models can be used as a guide for making patient-specific surgical decisions. This and follow-on studies will address long-standing questions of speech outcomes following surgery and the effect of growth and maturation of the VP structures on VP function.